When we were kids, we opened gifts at our birthday parties. The party came to a grinding halt while the birthday boy or birthday girl opened presents. It was fun if you were the gift getter, not so much if you wanted to run and play and continue with the party.
Here in NY most kids have parties somewhere other than the house. The gifts are dropped off in a bin or a table and then moved directly to the car after the party. It is just the way it is. Time is money -- parents are paying by the hour for these party locations. At first it seemed weird but I actually like it better. There isn't worry your gift isn't as good or embarrassment if no one likes it. Plus the party remains fun.
Turns out Miss Manners believes that is the way it should be. In a recent column she said she "considers killing the public opening to be a mercy." She also "commends those who have noticed the problem and taken the step of abolishing the public show."
Thanks Miss Manners :).